In most cases, the recipe for a true crime book is very simple: take innocence, add a figure of evil, and stir. In the case described in Robert Kolker’s Lost Girls: An Unsolved American Mystery, though, none of the ingredients were in the pantry. First of all, as far as identifying the killer is concerned, there is very little to go on: no DNA, disappearances years old, no strange men spotted in trucks. Even local rumor comes up rather short on innuendo and conjecture. All we have is three women’s bodies buried in suspiciously similar circumstances, another woman who was last seen running terrified into the night, and a lot of shrugging from the local cops.

Kolker couldn’t even rely on the standard device of the crime book, a flat portrait of the beautiful, innocent victim, to give him some cheap pathos. The victims of the putative serial killer at the center of the case were sex workers. And as sex workers, in the world at large, the victims bear the cultural baggage attached to their livelihood — the paradoxical invisibility that comes with it. It’s not an accident, as Kolker’s book charts quite well, that until the bodies turned up the police were less than enthusiastic about finding these women. The reasoning is somewhere between deliberate indifference and blaming the victim. Lead the life of the disappeared, and don’t be surprised when, well, you know.

Yet it’s the very invisibility of these subjects that opened their stories to a book-length telling. It is no accident, for example, that we are nearly halfway through the book before we get to the meat of the investigation. Before that point, Kolker’s task is to bring into focus the five women who disappeared — Maureen, Melissa, Megan, Amber, and Shannan — and what he manages to elicit from their families and friends is the most nuanced, complex portrayal of prostitution in America I’ve ever read from a mainstream journalist.

In interviews, Kolker has said that he was unfamiliar with the nuances of the debate about sex work until he began reporting the Long Island serial killer story. I, for one, think that is a blessing. Among feminists the line is stark. On one side you have the kind of anti-trafficking advocate who believes that prostitution is a literal tool of the patriarchy, which transforms the abused and the disenfranchised into a “sex class” perpetually on-call for the powerful. On the other, you have the kind who insists that there is something valuable, liberating, even “empowering” in the work. Each camp tends to rely on the selective use of facts, and for anyone to cross the lines has become extremely rare.

In stumbling out into the no-man’s-land without preparation, Kolker is able to hold several opposing thoughts in his head at once. First, he does not hold back in addressing, quite directly, the fact that there was dysfunction in these women’s lives before they walked away into the dark. They were drug addicts and teenage mothers and petty criminals. They suffered. But he can also see that within those circumstances they had moments of strength and self-assurance. Dysfunction is not wholly determinative; it didn’t have to end this way. There’s hope, for example, in the makeshift family Amber cobbled together from a group of recovering addicts. Megan, though in and out of juvenile prison for shoplifting, managed to garner a fatherly affection from her arresting officer. Maureen was close to a sister who wishes she’d answered Maureen’s call to pick her up on that last night. Melissa loved making hair into cornrows, and Shannan played Miss Hannigan in high school.

Indelible little details like that aren’t just the mark of good reporting; they’re the sign of a reporter who actually wants to describe these women as they were, not as ciphers in a story as old as Jack the Ripper, targets waiting to be hit. The rest of the book is vividly drawn too, of course — a local doctor who seems to know too much gives Kolker a character to follow, if not quite a suspect or, indeed, a villain.

It’s a sign of how much shape Kolker gives the victims that you rather miss them when they go. At the end, he allows himself a small bit of editorializing. “What’s clear is that no good can come from pretending that the people who participate in prostitution don’t exist,” Kolker writes. “That, after all, is what the killer was counting on.” It may be little comfort, but with this book, Kolker’s certainly offered what he can as antidote: for the 200 or so pages he gives them, those “girls” exist.